Quins managed to edge the European Champions Cup encounter at the Ricoh Arena on Saturday but the victory came at a price with Brown suffering an injury to his eye.
Harlequins director of rugby John Kingston has admitted Brown suffered a blow and will now undergo further assessment to establish the full extent of the problem.
He said: "Mike's got a bang on the eye and was reporting slight blurred vision, so we just wanted to make sure he's all right with that. He's gone to get a check-up."
England kick-start their Six Nations campaign when they travel to Rome to face Italy on February 4.
Red Rose head coach Eddie Jones will be keeping a close eye on Brown's fitness ahead of that trip to the Eternal City.